This invention relates to improvements in molded type underwater motors for use in, for instance, wells.
FIG. 1 is a sectional view of the principal portion of a molded type underwater motor of the sort disclosed by Published Japanese Patent appl. No. 58-51755. The molded type underwater motor shown therein comprises a stator 1 consisting of a stator core 2 and a stator coil; a can 3 of thin stainless steel inserted into the inner periphery of the stator core 2; a resin molded member 4 of unsaturated polyester resin enveloping the outer periphery and side of the stator core 2 and the perimeter of the coil end 5 of the stator coil; a screw receptacle 7; a rotor 8; a rotor shaft 9; a bracket 10 rotatably supporting the rotor shaft 9 through a bearing 11; a fastening bolt 12; and a powder coated layer 13 of polyethylene or polypropylene built up on the perimeter of the coil end 5, the whole body being molded within the resin body 4 after the powder coated layer is formed.
The operation of this molded type underwater motor will subsequently be described. Unsaturated polyester resin is employed as the resin molded body 4 to encapsulate the perimeter of the coil end 5 at low pressures and low temeratures. The powder coated layer 13 of polyethylene or polyproplene is provided between the resin body 4 and the coil end 5. If water infiltrates through the mold member 4, it will be kept out of the coil by the layer 13.
Moreover, an encapsulating liquid A injected about the perimeter of the rotor 8 and the can 3 is used to prevent water from infiltrating into the stator core 2.
With the molded type underwater motor thus constructed, it is difficult to arrange the can on the inner periphery of the stator core so as to prevent water from infiltrating through the inner periphery of the stator core. Since the can is made of stainless steel, it is also uneconomical.